41 Board formats The latest emerging board format for embedded computing in uncrewed systems is VNX+ or VITA90. This is built on VME standards that have boards connected to a backplane to flexibly build up a system. The cards can be sensors, processors or switches, along with a power-supply card. VNX+ is an enhancement of the VITA 74 specification for small form-factor boards that can fit into the fuselage of a UAS. The main changes are to increase the thermal envelope from 20 W to 80 W for each card, allowing more powerful processors and GPUs to be used, and also to increase the signal speed across the backplane to 110 GHz to support higher data-rate protocols, such as gigabit Ethernet. The VNX standard form factor is 89 mm x 78 mm, with height options of 12 mm or 19 mm – about one-third of the volume of a traditional, 3U plug-in card. The specialist connectors have a 1.27 mm pitch for the smaller size, and they are designed to be high-speed and highdensity with an open-pin field design. Development chassis are providing the ability to combine different VNX+ boards to test the overall system performance. The VNX+ specification ensures the boards are compliant with the modular open systems architecture (MOSA) that allows interoperability with a wide range of software and sensors. The eight-slot backplane in the development chassis supports up to 10GBASE-KX/40GBASE-KX4 Ethernet and PCI Express 4.0 with six well-defined payload slots that can accommodate a range of cards, one switch slot and a PSU slot. An internal power supply, gigabit Ethernet switch, a VITA 46.11 chassis manager, maintenance port aggregator and front-panel I/O are also integrated into the chassis. The chassis supports the 19 mm x 320 pin, 19 mm x 400 pin, 39 mm x 320 pin and 39 x 400 pin plug-in cards, while the 320 pin variants support the hybrid aperture connectors with custom connector pinouts that fit into the existing chassis slot, or aperture. The unit has handles for easy transport in the lab and field, a 5o tilted card cage and locking retainers to secure modules in slots against blind-mate connectorspring forces. It uses directed air to cool modules, either with or without metal enclosures, and offers built-in I/O, including unique external I/O (UEIO) direct device control without additional mezzanine cards. A small number of VNX+ boards are available commercially, but the flexibility of the standard lets engineers design and build their own specialist sensor or security boards while using commercial compute, switching and power boards to simplify the development process. These include VNX+ boards using a GPU with 1024 cores running up to 918 MHz, providing general-purpose processing. The chip includes 32 thirdgeneration Tensor cores for AI machine learning, achieving a performance of up to 100 TOPS (with 8 bit integer data). Despite the small form factor, the board includes a self-encrypting drive that supports data encryption, providing protection for sensitive information without significantly affecting read/write speeds to the drive. Embedded computing tech | Focus Uncrewed Systems Technology | December/January 2025 The VNX+ module (Image courtesy of Samtec) A VNX+ development chassis (Image courtesy of Elma Electronics)
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